Move referrer policy to a different field when serializing.

components/sessions/core/serialized_navigation_driver.h

Index: components/sessions/core/serialized_navigation_driver.h
diff --git a/components/sessions/core/serialized_navigation_driver.h b/components/sessions/core/serialized_navigation_driver.h
index fafaa27d29dfb09f41bfe89b09464da6c503ecbc..8702f867aa51aeb3928699539cf30af916b52d18 100644
--- a/components/sessions/core/serialized_navigation_driver.h
+++ b/components/sessions/core/serialized_navigation_driver.h
@@ -25,6 +25,18 @@ class SESSIONS_EXPORT_PRIVATE SerializedNavigationDriver {
   // Returns the default referrer policy.
   virtual int GetDefaultReferrerPolicy() const = 0;
 
+  // Maps current referrer policies to old values to work around
+  // crbug.com/450589. Returns false if the referrer should be stripped.
+  virtual bool MapReferrerPolicyToOldValues(
+      int referrer_policy,
+      int* mapped_referrer_policy) const = 0;
+
+  // Sanitizes a referrer policy that might either be in the old or the new
+  // format. Returns false if the referrer should be stripped.
+  virtual bool MapReferrerPolicyToNewValues(
+      int referrer_policy,
+      int* mapped_referrer_policy) const = 0;
+
   // Returns a sanitized version of the given |navigation|'s encoded_page_state
   // suitable for writing to disk.
   virtual std::string GetSanitizedPageStateForPickle(